Curved structure located between two intermediate supports; it can resist more compression force than the lintel and allows the use of bigger spans.

semicircular (Roman), segmental (less than half a circle), or pointed (Gothic).

Parts

1. Keystone

2. Voussoir

3. Back

4. Impost

5. Intrados

6. Rise

7. Clear span, "Bay"

8. Abutment

• Circular arches from a single center.

• Circular arches of more than one center.

• Non-circular arches of two centers.